<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="vue.js"></script>
</head>
<body>
    <div id="app">
        <my-com></my-com>
    </div>

    <div id="app2">
        <my-com></my-com>
    </div>

    <div id="app3">
        <my-com></my-com>
    </div>
</body>
<script> 

Vue.component('myCom', {
    template:`<button @click="count+=1">{{ count }}</button>`,
    data() {
        return {
            count:0
        }
    }
});

new Vue({
    el: '#app'
})

new Vue({
    el: '#app2'
})

new Vue({
    el: '#app3'
})
</script>
</html>